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Miller 254678 Screw-On Tank Cap with Vent and Lanyard — main product image
Miller

Miller 254678 Screw-On Tank Cap with Vent and Lanyard

★★★★★5.0 (1 reviews)

Keep your tank sealed tight with the Miller 254678 screw-on cap featuring a built-in vent and attached lanyard.

$77.99*
✓ In Stock on Amazon.com
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*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

The Miller 254678 is a screw-on tank cap engineered as a direct replacement for Miller welding and powersports equipment. Built from alloy steel, it offers a level of durability that outlasts plastic alternatives, standing up to workshop conditions, chemical exposure, and everyday handling without cracking or degrading. The 3.5-inch twist-on design threads securely into place without tools, making cap removal and replacement quick during refills or maintenance.

Two practical features set this cap apart from a basic plug. The integrated vent allows air to enter the tank in a controlled manner, preventing the vacuum buildup that can slow or stop fluid flow during operation. Meanwhile, the attached lanyard keeps the cap connected to your equipment at all times, eliminating the common frustration of misplaced caps in busy shop environments. As a purpose-built Miller replacement part, it is designed to match original equipment specifications for a reliable, no-fuss fit.

Specifications

Brand
Miller
Model
254678
Material
Alloy Steel
Size
3.5"
Closure Type
Twist-On
Vent
Yes
Lanyard
Included

Pros & Cons

👍 Pros

  • Alloy steel construction resists corrosion and withstands rugged use
  • Built-in vent prevents vacuum lock for smoother fluid flow
  • Attached lanyard keeps the cap tethered so it cannot be misplaced
  • Twist-on closure provides a secure, tool-free seal
  • Compact 3.5-inch size fits standard Miller tank openings

👎 Cons

  • Only fits tanks with a matching 3.5-inch screw-on opening, limiting cross-compatibility
  • Alloy steel adds weight compared to plastic replacement caps
  • No gasket or o-ring information provided, so long-term seal integrity is unclear
  • Lanyard length is fixed and may not suit all mounting configurations

Frequently Asked Questions

This cap measures 3.5 inches in diameter and uses a screw-on twist closure. Verify your tank opening size before purchasing to ensure a proper fit.
The cap is constructed from alloy steel, providing durable and corrosion-resistant performance for tank applications.
The built-in vent allows controlled airflow into the tank, preventing vacuum lock during fluid dispensing and ensuring smooth, consistent flow.
Yes, the lanyard is included and attached to the cap, keeping it tethered to your equipment so it won't get lost or dropped during use.
The Miller 254678 is designed as a Miller replacement part. Thread compatibility with non-Miller tanks is not guaranteed, so check your equipment specifications before ordering.

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